The primary aim of the research proposed to develop methods for assessing the behavioral mechanisms underlying medication-induced decreases in alcohol intake in humans. Although new medications are being introduced to control alcohol intake in alcoholics, little is known about how these medications actually change the effects of alcohol in people. The purpose of this study is to develop a behavioral assessment battery to measure urge and stimulation in social drinkers during a field alcohol self-administration protocol. The utility of these behavioral measures of stimulation and urge will be assessed in social drinkers, pretreated with one of three doses of naltrexone. Naltrexone is an FDA approved pharmacotherapy for lowering alcohol consumption.